Re: [Libguestfs] [supermin] [PATCH] ext2: check for needed block size

Check early that there are enough free blocks to store each file, erroring out with ENOSPC if not; this avoids slightly more obscure errors later on. --- src/ext2fs-c.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/src/ext2fs-c.c b/src/ext2fs-c.c index f01ca9d..e45980a 100644 --- a/src/ext2fs-c.c +++ b/src/ext2fs-c.c @@ -52,6 +52,9 @@ /* fts.h in glibc is broken, forcing us to use the GNUlib alternative. */ #include "fts_.h" +/* How many blocks of size S are needed for storing N bytes. */ +#define ROUND_UP(N, S) (((N) + (S) - 1) / (S)) + struct ext2_data { ext2_filsys fs; @@ -629,6 +632,7 @@ ext2_copy_file (struct ext2_data *data, const char *src, const char *dest) errcode_t err; struct stat statbuf; struct statvfs statvfsbuf; + size_t blocks; if (data->debug >= 3) printf ("supermin: ext2: copy_file %s -> %s\n", src, dest); @@ -649,6 +653,20 @@ ext2_copy_file (struct ext2_data *data, const char *src, const char *dest) caml_copy_string (data->fs->device_name)); } + /* Check that we have enough free blocks to store the resulting blocks + * for this file. The file might need more than that in the filesystem, + * but at least this provides a quick check to avoid failing later on. + */ + blocks = ROUND_UP (statbuf.st_size, data->fs->blocksize); + if (blocks > ext2fs_free_blocks_count (data->fs->super)) { + fprintf (stderr, "supermin: %s: needed %lu blocks (%d each) for " + "%lu bytes, available only %llu\n", + src, blocks, data->fs->blocksize, statbuf.st_size, + ext2fs_free_blocks_count (data->fs->super)); + unix_error (ENOSPC, (char *) "block size", + data->fs->device_name ? caml_copy_string (data->fs->device_name) : Val_none); + } + /* Sanity check the path. These rules are always true for the paths * passed to us here from the appliance layer. The assertions just * verify that the rules haven't changed. -- 2.5.0